Process and apparatus for the vacuum production of magnesium



Aug. 3, 1948. BASSEREAU 2,446,403

PROCESS AND APPARATUS FOR THE VACUUM PRODUCTION OF MAGNESIUM Filed June18, 1945 -lNVEN TOR. 94oz flmmaua BY ATTORNEY.

Patented Aug. 3, 1948 PROCESSAND APPARATUS FOR THE VAC- UUM PRODUCTIONOF MAGNESIUM Georges Bassereau, Paris, France, assignor to SocieteDEtude Pour LIndustrie Du Magnesium,

Paris, France Application June 18, 1945, Serial No. 600,031

France May 5, 1944 Section 1, Public Law 690, August 8, 1946 Patentexpires May 5, 1964 4 Claims.

The present invention relates to the treatment of metals in which themetallic vapors are condensed. It refers particularly to the manufactureof magnesium which is obtained by reduction of the ore and condensationof the metallic vapors which are thereby produced. Such operations haveto be carried out under vacuum. When they are finished, the atmosphericpressure is reestablished in the furnace, with the object of effecting afresh charging of the ore, and the condenser is withdrawn for collectionof the metal which is depositedtherein. The furnace is then againcharged and a fresh operation of reduction is commenced after an emptycondenser has been put in place.

However, if special precautions are not taken, several disadvantagesresult from this mode of operation.

At the end of the reduction operation, the metal gathered in thecondenser is at a high temperature, which can attain 650 C. in the caseof magnesium, and if the vacuum is broken at this moment, the metal iseasily oxidised and even nitrided, particularly in those parts of itdeposited in the pulverulent state.

If, on the contrary, it is desired to wait, before breaking the vacuum,until the metal has cooled to a temperature at which it will no longeroxidise in air (50-100 for example, in the case of magnesium), thereduction furnace is uselessly immobilised and moreover is allowed tocool,which increases the expenditure of heat for a latter operation.

On the other hand, the introduction of air at the movement when thefurnace is opened produces a movement of dusts towards the condenser.

The present invention has for an object to remedy these disadvantages,among others.

The invention consists in transferring the condenser, at the end of thecondensation operation, from the position which it occupies in thefurnace enclosure during this operation into an auxiliary chamberconstituting a sealed prolongation of said enclosure, this transfertaking place While leaving under vacuum the common enclosure of thefurnace and the auxiliary chamber, and in cutting off communicationbetween the chamber and the furnace by sealing means without opening theenclosure.

The furnace may then be opened and charged again, while maintainingunder vacuum the auxiliary chamber and consequently the condenseritself. Moreover, the condensed metal may be subjected to anyappropriate thermal treatment that may be desired. It is possibleparticularly to effect under vacuum the cooling of the metal, forexample until the chamber can be opened and the vacuum within it brokenwithout danger of alteration of the metal. An operation of fusion andrefining of the condensed metal may also be effected. 1

According to one mode of carrying out the method according to theinvention, these difierent thermal treatments to which the condensedmetal is subjected may be effected without separating the auxiliarychamber from the furnace. They may alternatively be advantageouslyeffected by displacing the chamber after the condenser has beentransferred into it, for example, in such manner as to enable thecondenser to be brought into other apparatus where the condensed metalcan be subjected, in the most favourable conditions, to the desiredthermal treatment.

The means used for the regulation of the temperature, in the thermaltreatment to which the metal is subjected after its condensation, may bemounted on the auxiliary chamber itself or mounted on' apparatus into.which the condenser is to be brought, while remaining under vacuum, bythe displacement of the auxiliary chamber.

In practice, the condenser in position in the furnace may be surroundedby a hood, the auxiliary chamber constituing a prolongation of thishood. The auxiliary chamber may be either connected in a permanentmanner to the hood or, preferably, be secured to it in a removablemanner in order to be separable from the furnace, as required. In thelatter case, the sealing means is mounted on the chamber itself, at theinlet of the latter, in order to accompany this chamber when it isseparated from the furnace and to enable it to remain under vacuumduring this displacement and the subsequent operations. In all cases,the sealing means is preferably placed beyond range of the vapors and isnot exposed to deterioration by these vapors and metallic deposits.Further, due to its spacing apart. from the flow of metallic vapors, thesealing, means may easily be cooled and may consequentlycomprisematerials suitable for ensuring complete fluid-tightness, but whichwould not resist.

high temperatures.

The condenser, when it is located in the aux-- iliary chamber, issubjected to a state of pressure: or vacuum which at all times is thesame internally and externally of the condenser. The latter thus hasnotto support any pressure stress andi can be a simple member easy todisplace, to 0001,,

I or to subject to other operation.

ciently cooled to permit opening of the auxiliary chamber, to remove thefull condenser. and insert an empty condenser. time in view of thepossibility of having, on the auxiliary chamber, intensive coolingmeans.ca'pable particularly of ensuring a more rapid cooling than that whichmight be obtained with the aid of temperature regulation means mountedon the furnace itself, about the condensation chamber.

This requires only 'ashort rated from one another at will. Sealing ofthe chamber I is effected by a movable closure plate 9, housed in theinterior of a, fluid-tight compartment in adjoining this chamber, thisplate being capable of ensuring by means of packings H the tight closureof said chamber 1, upon being moved, from the position 9a, to theposition 9b, shown in dotted lines.

1 Inv order to facilitate the movement of the closure 9 at the same timeas to ensure the satis- --factory operation of the packings H, some playWhen the auxiliary chamber is to be'separated I from the furnace afterthe condenser has been transferred into it and the sealing means closed,another chamber provided with an empty condenser can immediately besubstituted for it and a new reduction operation then begun. The auxiliary chamber, holding its condenser and maintained under vacuum canthen be brought for the subsequent treatment of the condensed metal toapparatus equipped for this treatment.

Particularly, the auxiliary chamber may be brought into an apparatusfixedly located, comprising especially intensive cooling means-whichwould have been difficult to mount on the chamber itself-and presentingmoreover the advantage of being adapted to serve for the cooling ofseveral auxiliary chambers.

If the treatment to which the metal is to be subjected (for example, afurther fusion) requires that the condenser should be transferred fromthe auxiliary chamber into an apparatus where this treatment is to beeffected, this transfer may be effected under vacuum by an analogousmanipulation to that which enabled the condenser to be passed from thereduction furnace into the auxiliary chamber, without breaking thevacuum, but for this manipulation effecting the-different operations inreverse order.

The invention, which has been described above more particularly in thecase where the vapors to be condensed are produced by the reduction ofan ore, is applicable, in a general manner, to all cases where thetreatment of metal results in the production of vapors to becondensedeither under vacuum or in an atmosphere of predetermined natureand/ or pressure. Similarly, the invention is applicable where it isrequired only to'effect a simpl operation of distillation.

The foregoing and other advantageous features of the invention willappear more clearly in the following description, with reference to theattached drawing, showing, by way of example and without limitation,apparatus for carrying out the method according to the invention.

The drawing shows diagrammatically, in section, a reduction furnaceprovided. with a hood and auxiliary chamber. The furnace l is constiisleft between thev closure and its packings until th closure occupies itsposition 8b. The grip of the packings on the closure is effected whenthe closure has been brought to 9D, for example by means of screwclamps, not shown, operated from outside and causing the closure to bearon its seator clamping it between the packings.

I-he closure, when it is placed in the position 9a, allows freedisplacementof the condenser at the end of the condensation period, andwithout affecting the state of vacuum of the furnace and the chamber,this displacement beingi fifectedgfor' and the chambers conjoined to beevacuated. I

Rollers 2-D mounted in the hood '5 and chamber 1- support the condenserin proper relation t c-the opening in the furnace.

After the condenser has been transferred into this chamber so as tooccupy the position ib, the closure is moved into the position 919 andatmospheric pressure can again be admitted to the furnace withoutmodifying the state of vacuum exist ing in the chamber 1.

By Way of example, cooling means for the auxiliary chamber 7,constituted by a chamber for the circulation of water, are shown at M.

The whole of the auxiliary chamber can be displaced by means of rollersi5 after having been disconnected from the furnace by disengagemento'f-the connecting means 8.

[In the case where the cooling of the auxiliary chamber is effected bycooling apparatus (not shown) serving several chambers and placedat somedistance from the furnace, the cooling means M may be omitted.

What is claimed is:

1. Apparatus for the manufacture of magnesium or the like that includesthree chambers of whichth'e secon'd'is constructed to be conjoined andsealed to the first and moved into the third, evacuating means toevacuate the three chambers, heating means to .maintain the firstchambers at a temperature at which the metal is vaporized, cooling meansto maintain the second and third chambers at a temperature at which themetal is condensed, transport means to move the second chamber withinthe third, and a closure to seal the second within the third.

2. A method of producing magnesium thatineludes vaporizing magnesium inone of two conjoined zones free of reactive oxygen, condensing thevapors of magnesium under vacuum .in'the second of the two con-joinedzones until it"is' charged with condensed magnesium, establishing vacuumand a coolingtemp'erature in athirdzone conjoined in sealed relation tothe first and com municating with the second, and then moving andsealing the second zone within the third zone and cooling it there untilit may be exposed to the air.

3. Apparatus for the manufacture of magnesium that includes a furnacewherein magnesium ore is reduced and the metallic magnesium isvaporized, an opening in one end of the furnace providing for the escapeof magnesium vapors therefrom, a condenser constructed and arranged tofit into the opening in the furnace and to seal the said opening so thatmagnesium vapors escaping from the furnace pass into the condenser, saidcondenser projecting outwardly from the wall of the furnace and beingsurrounded by an extension on th furnace, cooling means surrounding theextension, a wagon having a chamber open at one end and constructed andarranged to make sealing engagement with said extension at said openend, closure means for the wagon chamber constructed therein near theopen end thereof, said wagon chamber having an outlet for evacuation,said condenser having an outlet for evacuation of its own interior andthat of the furnace, and supporting means on which the condenser may bemoved into the wagon chamber for sealing under vacuum prior to thebreaking of the seal between the said extension and the said chamber.

4. Apparatus for the manufacture of magnesium or the like that includesthree chambers of which the first is a metal vaporizing furnace havingan extension, the second is constructed to be conjoined to and open intothe first within the extension, and received within the third, and thethird is constructed to be sealed to the extension and separable fromit, evacuating means including a single outlet in the third chamber forevacuating the three chambers, cooling means to maintain the second andthird chambers at a temperature at which the metal is condensed, motionimparting means to move the second chamber into the third, a closure toseal it therein, and transportation means supporting the third chamberfor movement away from the second.

GEORGES BASSEREAU.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 25 1,432,842 Donaldson Oct. 24,1922 2,258,374 Amati Oct. 7, 1941 Certificate of Correction Patent No.2,446,403.

GEORGES BASSEREAU t errors appear in t equmng correctlon a It is herebycertified tha he printed specification of numbered patent r the above sfollows: Column 1, hne 32, for the Word latter read la 7*, llne 35, formovement rea moment; colum 4, line 62, for c ambers at read chamber at,and that the Stld Letters Pate ese corrections thel em that be read withcord of the case in the THOMAS F. MURPHY,

Assistant Commissioner of Patents.

August 3, 1948.

